1. Field of the Invention
The present invention relates to a method for the diagnosis of diseases using magnetic entities to target one or more specific molecules that are indicators of a specific disease. The resulting diagnosis may be carried out in vitro, using for example microchip analysis, or in vivo where for example, magnetic entities are injected into a subject. This invention also relates to security check and toxicity analysis. Some embodiments of this method may be used for identifying and quantifying the presence of a target molecule or target molecules in a single sample and elucidating conformational information about such target molecules.
2. Background of the Invention
Magnetic entities, most often as particles and in other forms such as rods and shells, are widely used in medical diagnosis and imaging. Usually they are conjugated with ligands that specifically target one or more molecules (receptors) which serve as indicators for certain diseases or are representative of biological hazards. One major challenge is to distinguish the signal that is specific to magnetic entities that are bound to the target molecules from the background signal of free, unbound magnetic entities. When such a distinction cannot be efficiently achieved, the alternative is to use physical separation to isolate the bound magnetic entities from the free magnetic entities. However, such a procedure is highly undesirable for most applications, due in part to excessive toxicity and increased cost.
Existing methods used to measure specific binding, without the use of separation techniques include: nuclear relaxation contrast, magnetic particle relaxation contrast, nonlinear response of susceptibility, and remanence detection. However, all of these methods have limitations which prevent their broad use in clinical settings. For example, nuclear relaxation contrast has poor sensitivity because of the intrinsically weak signal of nuclear spins. Magnetic particle relaxation contrast is based on the difference in relaxation times between the bound magnetic particles and the free magnetic particles. Associated shortcomings include a small difference in relaxation time and a narrow time window during which the measurement can be performed. Also, it is known that susceptibility response is severely affected by the size distribution of the particles. Remnant field measurement offers high sensitivity, but a strong background signal from the free particles results in a lower sensitivity and selectivity.
The production of a method capable of revealing multiple types of target molecules based on their different binding properties would be particularly well received, and embodiments of the herein presented method are believed to overcome certain above mentioned limitations by the utilization of force-induced contrast in magnetization measurements.